Apparatus for generating a pulsating air

Abstract: A method and an apparatus for generating a pulsating air by communicating an air passage intermittently by rotating a valve (4, 4A, 4B) while feeding air into a casing or discharging air from the casing (3, 3A, 3B, 3C) by a blower (6) connected to a connecting port of the casing (2a - 2g). The air passage extends from the connecting port for the blower (2a - 2g) to a transmitting port (1, 1A, 1B) of the casing (3, 3A, 3B, 3C) for transmitting a pulsating air. The apparatus for generating a pulsating air is comprised of a casing (3, 3A, 3B, 3C) provided with a connecting port for a blower (2a - 2g) and a transmitting port for a pulsating air (1, 1A, 1B). The connecting port (2a - 2g) is connected with a feeding side of the blower (6) or a suction side of the blower (6). The valve (4, 4A, 4B) is designed to be operated so as to intermittently communicate the air passage.

Description: Field of the Invention The present invention relates to apparatus for generating pulsating air, referred to herein as a pulsating air generator. Prior Art Middle or low frequency pulsating air increases the efficiency of heating and drying treatment of powdered or granular materials when operated on the materials while they are heated or dried. Besides that, pulsating air can be applied to remove dust and the like mixed with powdered or granular materials or to remove dust and the like attached on the surface of articles and machines, and pulsating air is expected to be utilized in various fields in future. A speaker type pulsating air generator which generates air oscillation by electrically vibrating a cone and a diaphragm type generator which produces air oscillation by reciprocating a diaphragm of a desired figure by utilizing the spring power or the electro-magnetic power of a solenoid have been proposed. However, the oscillating pressure of pulsating air produced by such a speaker type or a diaphragm type generator has been very low because the cone has been merely vibrated or the diaphragm has been merely reciprocated. It has been in practice difficult to utilize a pulsating air of such a low pressure for various fields of industry due to the fact that the pulsating air doesn't work effectively when utilized to remove dust attached on articles. A diaphragm can be enlarged, for example, to heighten the oscillating pressure of a pulsating air. However, there has been a definite limit to heightening the oscillating pressure and sufficient pressure can't be obtained when the air oscillation is generated by the movement of the diaphragm. Further the whole apparatus becomes too large to handle easily when a large diaphragm is used. Still further, mechanical vibration and noise of the whole apparatus caused by reciprocation of an enlarged diaphragm become large. Therefore, enlarging a diaphragm has inconveniences and also can't solve the above-mentioned problems appropriately. US-A-4 881 574 discloses a pulsating air generator with the features of the preamble of claim 1. The Invention The present invention has been proposed in view of the above-mentioned problems. Accordingly, the object of the present invention is to generate a pulsating air of high oscillation pressure by a facile and compact apparatus. In this specification, one of most typical pulsating air is a stationary wave of middle or low frequency. According to the invention, there is provided a pulsating air generator of the axial flow type comprising a casing having an exit port for applying pulsating air pressure and at least a blower port connected with a suction port and/or an emission port of a blower, and within the casing a valve disk drivable in rotation about its axis by a motor and containing a hole together with valve means by which communication between the exit port and the blower port via a hole can be controlled, characterised in that the valve means comprises, in a plane directly adjacent that of the valve disk and interposed between the valve disk and the wall of the casing, a spacer having angularly separated holes for selective alignment and non-alignment with a hole in the rotatable valve disk, whereby the exit port can be communicated or not with the suction port and/or the emission port in accordance with controlled rotation of the valve disk. The pulsating air which is generated by the apparatus may be one of the following, pulsating air comprising a positive wave and negative wave, pulsating air comprising negative pressure, or pulsating air comprising a positive wave. In the apparatus in accordance with the invention, the oscillation pressure of the pulsating air generated from the transmitting port can be easily made high by heightening air pressure supplied into the casing from the blower or suction pressure sucked into the blower from the casing. Therefore, a pulsating air with high oscillating pressure can be obtained without enlarging the casing and other parts. Further, large mechanical vibration and noise aren't generated at parts and members such as the casing when pulsating air is generated because parts such as a large diaphragm which mechanically vibrates are unnecessary. In the apparatus for generating pulsating air in accordance with the invention, the valve disk may be designed to be stopped at the position where a transmitting port and a connecting port are communicated with each other. Continuous air discharge or air suction can be executed through the transmitting port. Therefore, such apparatus can be also used for feeding air continuously or for sucking air continuously, other than generating pulsating air. Description of Embodiment In the accompanying drawings:- Fig. 1 is a sectional plan view of one embodiment of a pulsating air generator according to the present invention. Fig. 2 is a sectional view taken along line X-X of Fig. 1. Fig. 3 is a perspective and partial exploded view of the pulsating air generator of Fig. 1. Fig. 4 is a sectional view of the pulsating air generator showing one condition where the valve disk is rotated from the position shown in Fig. 2. Fig.5 is a sectional view showing the condition where the valve disk of the pulsating air generator in Fig.1 is rotated. Figs.6 (a) and (b) show the wave shape of a pulsating air generated from the pulsating air generator shown in Fig.1. Fig.7 is a sectional view of other embodiment of a pulsating air generator according to the present invention. Fig.8 is a sectional view of a further embodiment of a pulsating air generator according to the present invention. Fig.9 is a sectional view showing the condition where the valve disk of the pulsating air generator shown in Fig.8 is rotated. Fig.10 shows the wave shape of a pulsating air generated from the pulsating air generator of Fig.8. Fig.11 shows other wave shape of a pulsating air generated from the pulsating air generator of Fig.8. Fig.12 is a sectional view showing other embodiment in which the pulsating air generator of Fig.1 is employed. Fig.13 is a sectional view showing a further embodiment of a pulsating air generator according to the present invention. Fig.14 is a sectional view showing one condition where the valve disk of the pulsating air generator shown in Fig.13 is rotated. Fig. 1 is a sectional plan view of one embodiment of a pulsating air generator A according to the present invention. Fig. 2 is a sectional view taken along line X-X of Fig. 1. Fig. 3 is a perspective and partial exploded view of the pulsating air generator A . The pulsating air generator A is provided with a casing 3 having a transmitting port 1 for a pulsating air and two ports 2a, 2b connecting with a blower 6, a valve disk 4 in the casing 3, a driving motor 5 for driving and rotating the valve disk 4, and the blower 6 for feeding air into the casing 3 and for discharging air from the casing 3. Several kinds of blowers such as Root's Blower and so on can be applied as the blower 6. In the present invention any blower which can feed air at a fixed positive pressure and suck air at a fixed negative pressure may be used. Therefore, a vacuum pump can be considered as a blower in the present invention. The casing 3 is comprised of a main body 3a of cylindrical shape with its front side opened and a front cover 3b connected to the front side of the main body 3a with flanges. The transmitting port a pulsating air 1 is provided at an appropriate position of the front cover 3b which corresponds to a front wall 30a of the casing 3. A short tube 7 is provided at the transmitting port 1 when required and is used to connect with a pipe 8c. Two connecting ports 2a, 2b for the blower 6 are provided at right and left sides of a back wall 30b of the casing 3 and each of them 2a, 2b has a short tube 7a, 7b respectively. The connecting ports 2a, 2b are connected with a suction port 6a and a feeding port 6b of the blower 6 via pipes 8a, 8b respectively. Air can be fed into the casing 3 and discharged from the casing 3 by this construction. The transmitting port 1 and the connecting ports 2a, 2b are provided at the walls 30a, 30b which face the front 4a and the back 4b of the valve disk 4 respectively. The pipes 8a, 8b, 8c can be neatly connected in such a way that they don't project out of the outer circumference of the casing 3. The valve disk 4 can rotate freely in the casing 3 because it is supported by a rotating axis 9 which is connected with a driving axis 5a of the driving motor 5. A spacer 10 is interposed between the back 4b of the valve disk 4 and the back wall 30b of the casing 3. Long circular holes 10a, 10b are provided at right and left sides of the spacer 10. When each long hole 10a, 10b faces the connecting ports 2a, 2b of the casing 3, these ports are communicated. The valve disk 4 is formed circular so that the disk 4 can close both connecting ports 2a, 2b by blocking the long holes 10a, 10b of the spacer 10 at the same time. The valve disk 4 is provided with a hole 40 for communication which is circular and is formed about the same size as the connecting ports 2a, 2b for the blower. The hole 40 is communicated with respective long holes 10a, 10b of the spacer 10 when the valve disk 4 is rotated. On the other hand the hole 40 can be positioned at the place where it doesn't communicate any of the holes 10a, 10b. One example of the driving motor 5 is a motor with a brake which can fix the valve disk 4 at a fixed angle of rotation. Preferably, the motor of which rotation speed can be changed by inverter control and so on is applied. Sensors C1, C2 are provided so as to be faced or in proximity to outer ends of the rotating axis 9 as means for controlling the driving motor 5. The sensors C1, C2 are designed to detect the position where the hole 40 of the valve disk 4 faces the connecting port 2a as shown in Fig.1 and the position where the hole 40 faces the other connecting port 2b as shown in Fig.5. The motor 5 can stop and keep the axis 9 and the valve disk 4 under the condition where the sensors C1, C2 detect such positions. One embodiment of the sensors C1, C2 is a photoelectric type which detects reflecting surfaces 11a, 11b provided on the axis 9. However, a proximity switch or a limit switch which detects by a mechanical contact can be used as the sensors C1, C2. The above-mentioned pulsating air generator A operates as described hereunder. The valve disk 4 is rotated in a fixed direction while the blower 6 connected to the casing 3 is operated. The hole 40 of the valve disk 4 is also revolved around the axis 9 and its position changes accompanied with the rotation of the valve disk 4. When the hole 40 of the valve disk 4 faces the long hole 10a of the spacer 10, the connecting port 2a for the blower 6 is communicated with the inside of the casing 3 as shown in Fig.1, air in the casing 3 being sucked by the blower 6. On the other hand, the connecting port 2b is closed by the valve disk 4. Therefore, negative pressure which sucks open air from the transmitting port 1 is generated in Fig.1. The duration when negative pressure is generated is the period when the hole 40 of the valve disk 4 is located within a range RA1 as shown in Fig.2. Then the hole 40 of the valve disk 4 is located where the hole 40 faces neither of the long holes 10a, 10b of the spacer 10 when the valve disk 4 is further rotated, as shown in Fig.4. In such a condition, both connecting ports 2a, 2b are blocked by the valve disk 4 and air isn't discharged from or sucked into the casing 3. At this time, generation of negative pressure from the transmitting port 1 is stopped. Such a condition is kept while the hole 40 of the valve disk 4 is located in an area RB1 as shown in Fig.2. Then the hole 40 of the valve disk 4 moves into a position where the hole 40 communicates with the connecting port 2b via the long hole 10b of the spacer 10, as shown in Fig.5. In this case air with a fixed pressure is supplied into the casing 3 from the blower 6. Accordingly, air with a fixed pressure is discharged from the transmitting port 1. The duration of discharge is the period when the hole 40 of the valve disk 4 is located within an area RA2, as shown in Fig.2. When the hole 40 is located within an area RB2, discharge of air from the transmitting port 1 is stopped. When the valve disk 4 is continuously rotated as mentioned above, a cycle comprising sucking air from the transmitting port 1 by negative pressure, stopping sucking, discharging air from the port 1 at a fixed pressure, and stopping discharging is repeated in series. Consequently, depressurizing and pressurizing are intermittently repeated at the transmitting port 1 and a pulsating air is transmitted from the port 1. In such a pulsating air, positive pressure and negative pressure are repeated alternately and its wave is formed like Fig.6(a) or (b). Its amplitude can be made large and its oscillating pressure can become high. The oscillating pressure of a pulsating air depends on the amount of suction and discharge of the blower 6. Accordingly the oscillating pressure can be easily made high by increasing the amount of suction and discharge of the blower 6. The timing of suction and discharge through the transmitting port 1, the timing of stopping those operations and so on depend on the diameters and positions of the transmitting port 1, the connecting ports 2a, 2b and the long holes 10a, 10b of the spacer 10. Therefore, a desired pulsating air can be obtained by controlling such conditions. According to the pulsating air generator A as mentioned above, the frequency of a pulsating air transmitted through the port 1 accords with the number of the rotation of the valve 4. The pulsating air can be easily and accurately settled at a desired frequency by controlling the number of the rotation of the driving motor 5. The valve disk 4 is a well-balanced circle and is continuously rotated in order to generate a pulsating air. Therefore, mechanical vibration and noise can't be caused in the casing 3 and other parts. The pulsating air generator A is sometimes required to be used as a simple instrument which supplies or sucks air other than as a generator for a pulsating air. In such a case, when the sensor C1 or C2 detects the position where the hole 40 of the valve disk 4 faces the connecting port 2a or 2b to be communicated each other and the valve disk 4 is stopped and kept at the position by operating a brake of the driving motor 5. If the valve disk 4 is stopped under the condition of Fig.1, air suction can be done continuously from the port 1. If the valve disk 4 is stopped under the condition of Fig.5, air can be continuously supplied. Therefore, the generator A can be widely utilized. In Fig.7, a cutout groove 41 is provided at the back 4b of the valve disk 4 of the generator A . Holes 42, 42a which is communicated with the cutout groove 41 are provided at appropriate positions of the outer wall of the casing 3. The generator in Fig.7 is designed such that compressed air supplied into the connecting port 2b from the blower 6 is discharged out of the casing 3 via the cutout groove 41 and the hole 42 while the blower 6 discharges air in the casing 3 through the connecting port 2a. When the valve disk 4 is rotated and the cutout groove 41 faces the hole 42a, the blower 6 sucks outside air through the connecting port 2a. Suction and discharge of the blower 6 can be smoothly done when the generator A is constructed as mentioned above. If the generator A is designed such that the valve disk 4 can fully close the connecting port 2b while air in the casing 3 is discharged through the connecting port 2a as shown Fig.1, the pressure of compressed air fed into the pipe 8b from the blower 6 can be heightened. Therefore, such construction is advantageous to heighten the oscillating pressure of a pulsating air generated at the port 1. Fig. 8 is a diagrammatic plan view of other embodiment of a pulsating air generator Aa according to the present invention. The pulsating air generator Aa is provided with a transmitting port 1 for a pulsating air at a front wall 30c of a casing 3A and a connecting port 2c for a blower at a rear wall 30d. A valve disk 4 having a hole 40 is located so as to touch or to be in close proximity to a spacer 10A provided with a hole 10c for communicating with the connecting port 2c. According to the pulsating air generator Aa , when a suction side of the blower (not shown) is connected with the connecting port 2c and the valve disk 4 is rotated, for example, air in the casing 3A is sucked into the blower and negative pressure is generated at the port 1 under the condition of Fig.8. When the valve disk 4 is further rotated and the hole 40 of the valve disk 4 is positioned at the place which doesn't meet the connecting port 2c, as showing in Fig.9, the port 2c is blocked by the valve disk 4 and negative pressure isn't generated at the transmitting port 1. When the valve disk 4 is continuously rotated, the conditions like Figs.8 and 9 as mentioned above are repeated alternately. Consequently, negative pressure is intermittently generated at the transmitting port 1 and a pulsating air under negative pressure can be appropriately transmitted through the transmitting port 1. Fig.10 shows the shape of a pulsating air generated under the above-mentioned condition. When such a pulsating air under negative pressure is utilized for eliminating dust attached on powdered or granular materials, for example, dust is removed from the materials by the oscillation of a pulsating air and simultaneously the removed dust is sucked into the casing 3A through the transmitting port 1 and collected. Therefore, such an apparatus is very useful. On the contrary, when the connecting port 2c is connected with feeding (discharging) side of the blower, a pulsating air with positive pressure, as shown in Fig.11, can be generated from the transmitting port 1. Fig.12 is a sectional view of an embodiment when a pulsating air generator A shown in Fig.1 is used in the same manner as a generator Aa is used as shown in Fig.8. According to the construction of Fig.12, one port 2b of two connecting ports 2a, 2b of the pulsating air generator A is blocked with an appropriate cover 12. Practically, it is the same as a generator with one connecting port 2a. According to such a construction, a pulsating air with only negative pressure or only positive pressure can be generated from the transmitting port 1 as described in the explanations of Fig.8 and Fig. 9. Fig.13 is a sectional view of other embodiment applying a pulsating air generator Ab according to the present invention. Both a transmitting port 1A for a pulsating air and a connection port 2d for a blower are provided at one side wall 3e of a casing 3B of the generator Ab . A valve disk 4A which is rotated by an axis 9A is provided with two holes 40A, 40B for ventilation in such a manner that the holes simultaneously face the transmitting port 1A and the connecting port 2d respectively. Two holes 10d, 10e are provided for a spacer 10B which is interposed between the valve disk 4A and the side wall 3e. According to the above-mentioned construction, when the valve disk 4A is rotated while the connecting port 2d is connected with the suction side or the feed side of the blower, both the connecting port 2d and the transmitting port 1A are opened and communicated in the casing 3B under the condition of Fig.13, negative pressure or positive pressure being generated from the transmitting port 1A. On the other hand, in Fig.14, the valve disk 4A blocks both the connecting port 2d and the transmitting port 1A simultaneously, and generation of negative pressure or positive pressure from the port 1A being stopped. Consequently, negative pressure or positive pressure is intermittently generated from the transmitting port 1A by continuously rotating the valve disk 4A and a pulsating air is transmitted. Embodiments of a pulsating air generator vary according to the present intention and their constructions aren't limited to the above-mentioned embodiments. For example, the pulsating air generator Aa as shown in Fig.8 is designed such that the connecting port 2c is opened and closed by the valve disk 4 while the transmitting port 1 is always opened. However, in the present invention, the connecting port 2c and the transmitting port 1 can be constructed reversely. That is, the transmitting port 1 is opened or closed by the valve disk 4 and the connecting port 2c is always opened. In such a case, the transmitting port 1 is operated as a connecting port for a blower by connecting the blower to the transmitting port 1 of the pulsating air generator Aa of Fig. 8. The connecting port 2c isn't connected with the blower and is operated as a transmitting port for a pulsating air. The following effects are apparent from the above-mentioned description according to the present invention. In the described apparatus for generating pulsating air, pulsating air can be generated from a transmitting port by intermittently communicating an air passage in a casing extending from a connecting port to the transmitting port by means of a valve while air is supplied into or discharged from the casing by a blower. Therefore, the oscillation pressure of a pulsating air can be easily made higher by heightening the suction pressure and discharge pressure of the blower without enlarging parts of the casing. As the result, a pulsating air at high oscillation pressure can be generated easily and appropriately and such a pulsating air can be applied for various industries, such as heating or drying powdered or granular materials. It is apparent that the pulsating air has unique characteristics and is widely used. Large parts, such as a diaphragm, which are mechanically reciprocated aren't required in order to produce a pulsating air. Therefore, mechanical vibration and noise aren't caused for instruments such as a casing and working conditions can be made better. The frequency of a pulsating air can be modified easily and randomly by changing the rotating speed of a valve. Further, a desired wave shape can be obtained by varying position, shape, size and so on of the openings of the transmitting port and the connecting ports. Comparing to the prior apparatus in which a part is reciprocated, the vibration of the apparatus can be reduced because the valve is designed to be rotated in the casing. The pulsating air generator can be also used in continuous air suck and in continuous air feed as well as in generating pulsating air.

Claims: A pulsating air generator of the axial flow type comprising a casing (3 or 3B) having an exit port (1 or 1A) for applying pulsating air pressure and at least a blower port (2a, 2b or 2d) connected with a suction port (6a) and/or an emission port (6b) of a blower (6), and within the casing a valve disk (4 or 4A) drivable in rotation about its axis by a motor and containing a hole (40 or 40A, 40B) together with valve means by which communication between the exit port (1 or 1A) and the blower port (2a, 2b or 2d) via a hole (40 or 40A, 40B) can be controlled, characterised in that the valve means comprises, in a plane directly adjacent that of the valve disk (4 or 4A) and interposed between the valve disk (4 or 4B) and the wall of the casing (3 or 3B), a spacer (10 or 10B) having angularly separated holes (10a, 10b, or 10d, 10e) for selective alignment and non-alignment with a hole (40 or 40A, 40B) in the rotatable valve disk (4 or 4A), whereby the exit port (1 or 1A) can be communicated or not with the suction port (6a) and/or the emission port (6b) in accordance with controlled rotation of the valve disk (4 or 4A). A generator according to claim 1, characterised in that the exit port (1) is directed forwardly from the casing and the blower ports (2a, 2b) are directed rearwardly, the spacer (10) lying in a plane immediately to the rear of the valve disk (4) and the holes (10a, 10b) in the spacer respectively communicating one with the suction port (6a) of the blower (6) and one with the emission port (6b) of the blower. A generator according to claim 1 or claim 2, characterised in that the hole (40) in the valve disk (4) and the holes (10a, 10b) in the spacer (10) provide for communication of the exit port (1) with the suction port (6a) and the emission port (6b) each over an arcuate range of rotation of the valve disk (4). A generator according to claim 3, characterised in that the valve disk (4) has a generally circular hole (40) and the spacer has arcuate holes (10a, 10b). A generator according to claim 4, characterised in that the arcuate holes (10a, 10b) in the spacer (10) are diametrically opposed around the spacer. A generator according to claim 1, characterised in that the exit port (1A) and the blower port (2d) are directed to the same side of the casing, and the valve disk (4A) has angularly separated holes (40A or 40B) for simultaneous alignment or non-alignment with angularly separated holes (10d, 10c) in the spacer (10B), whereby the exit port (1A) can be communicated or not with either the suction port (6a) or the emission port (6b) of the blower in accordance with controlled rotation of the valve disk (4A). A generator according to claim 1, characterised in that the valve disk (4) has, additionally to the hole (40), a cutout groove (41) adjoining the periphery of the valve disk, and the casing (3) has holes (42, 42A) in its side wall enabling air from the blower (6) to be discharged laterally from the casing via the groove (41) and holes (42, 42A).

Inventors: KOISHI YOSHITAKA, MURATA KAZUE, TADA HIROSHI, KOISHI, YOSHITAKA, MURATA, KAZUE, TADA, HIROSHI, KOISHI, YOSHITAKA, C/O K.K.MATSUI SEISAKUSHO, MURATA, KAZUE, C/O K.K.MATSUI SEISAKUSHO, TADA, HIROSHI, C/O K.K.MATSUI SEISAKUSHO
Applicants: MATSUI MFG CO, KABUSHIKI KAISHA MATSUI SEISAKUSHO
Application year: 1994
Main classification: F16K11
IPC codes: F26B21, B06B1, F16K11